It has also been suggested already to provide holes in plastic conduits and permit the water to trickle from those holes. Further, it is known to insert nozzles into holes made in the wall of conduits, such nozzles emitting a steady trickle of water.
Drainage pipes are conduits which have holes in the walls thereof or whereof the walls are porous. Such pipes are laid out underground, water in the soil e.g., in swampy terrain, percolates into the pipes and is conducted to a point of assembly.
The plastic conduits provided with outlet ports for trickle or dropwise emission of water have the disadvantage that they become frequently clogged by impurities in the water, the same is the case with nozzles provided on water conduits. This is likely to occur with drainage pipes.